Islamabad , Pakistan -LRB- CNN -RRB- -- The three security guards and the driver of an American development expert who was abducted in Pakistan on Saturday have been detained for questioning , a police official said Monday .

The four men are not considered suspects at this point , said the official , who asked not to be named because he is not authorized to speak to the media . Under Pakistani law , police can detain someone for up to 72 hours without charging them with a crime .

Investigators have no leads in the case and are not any closer to finding out what happened to the American , whom the U.S. Embassy identified as Warren Weinstein .

Weinstein was abducted early Saturday when gunmen , posing as neighbors offering food , pistol-whipped him and his driver and tied up his guards , U.S. Embassy and Pakistani officials said .

Weinstein works for J.E. Austin Associates Inc. , a U.S. consulting firm based in Arlington , Virginia , a Pakistani official said . He 's is a world-renowned development expert , with 25 years of experience , according to his company 's website . The site says he was heading what the company described as the `` Pakistan Initiative for Strategic Development and Competitiveness . ''

As Weinstein 's security guards prepared for the meal before the Ramadan fast early Saturday , three men knocked at the front gate and offered food for the meal -- a traditional practice among Muslims during the Ramadan holy month , according to senior Lahore police official Tajamal Hussain .

Once the gate was opened , the three men forced their way in while five other suspects entered the house from the back , Hussain said . The men tied up the three security guards and duct-taped their mouths , he said . They pistol-whipped the driver and forced him to take them to Weinstein 's room , where the men hit Weinstein in the head with a pistol , and forced him out of the house and into a waiting car , Hussain said .

He said Weinstein is in his 60s .

There has been no claim of responsibility nor any demands by any groups , according to senior police official Awais Ahmed .

Weinstein has lived in the residence in an upscale Lahore neighborhood for several years , Ahmed said .

Weinstein is a Fulbright Scholar in Belgium and is proficient in six languages , with a doctorate in international law and economics , according to his company website .

U.S. Embassy officials are working with Pakistani authorities on the case , Embassy spokesman Alberto Rodriguez said Saturday .

The U.S. State Department updated a travel advisory for Americans traveling and working in Pakistan this week , warning that extremist groups operating in the country were continuing to target U.S. and other Western citizens and interests .

It cited part of the reason for the advisory as `` reported '' abductions of U.S. citizens `` for ransom or personal reasons , '' including the kidnapping of a U.S. citizen in Lahore in June . No further details about that incident were released .

Abductions are not unusual in Pakistan , though those targeted are typically Pakistani rather than American or Western .

In early July , a Swiss couple was grabbed at gunpoint while traveling in the town of Loralai in the volatile southwestern Balochistan province , provincial officials said at the time .

Three weeks after their abduction , Pakistani authorities said they believed the couple was still alive .

Weinstein 's abduction follows another high-profile incident involving an American in Lahore .

Raymond Davis , a CIA contractor , was charged with killing two men in January but was released in March after compensation was paid to their families .

Journalists Nasir Habib and Shaan Khan and CNN 's Salma Abdelaziz contributed to this report .

@highlight

The men are not considered suspects at this time , a Pakistani police official says

@highlight

Gunmen abducted an American from his Pakistan residence Saturday , authorities say

@highlight

He is identified as Warren Weinstein , the U.S. Embassy says

@highlight

There has been no claim of responsibility , or demands